Central Banks know your positions: if someone thinks market is totally neutral and there is no bias against any trades that are being placed then here is an occasion in 1987 that you might be aware of. An FX trader from Bankers Trust in New York named Andy Krieger placed a huge bet against the Kiwi (NZD/USD.) Like George Soros bet against the Bank of England, he was aware of the total money supply of New Zealand. It is the presumption that Mr. Kreiger, "sold more Kiwis than the entire money supply of New Zealand." Hysterically, it's been alleged that "New Zealand's Finance minister telephoned Bankers Trust (his employer) to complain and beg for mercy."
Now having said that, do the central banks care about trades that are being placed by retail traders, the answer is 'No.' On the other hand, can the Central Banks take extreme measures to discourage this kind of speculation, 'Yes.' Central Banks can raise the overnight interest rates of their currencies overwhelmingly, say, for 500% while nominally permitting the tradings--which can create an effect of "Reflexivity."
So, there is huge risk involved in trading against a government. And again, retail traders have nothing to worry about--the notion that someone is always conspiring against your trades is a complete fallacy.
[Source: Foreign Exchange, A Practical Guide to the FX Markets]